MIPv6 node identifier: Mobile Node Identifier Option for Mobile IPv6 (MIPv6)
A Mobile IPv6 option that lets a mobile node identify itself with a name such as a user@realm NAI instead of only its home address.
Patel, A., Leung, K., Khalil, M., Akhtar, H., and K. Chowdhury, "Mobile Node Identifier Option for Mobile IPv6 (MIPv6)", RFC 4283, DOI 10.17487/RFC4283, December 2005, <https://www.rfc-editor.org/info/rfc4283>.
@misc{rfc4283,
series = {Request for Comments},
number = 4283,
howpublished = {RFC 4283},
publisher = {RFC Editor},
doi = {10.17487/RFC4283},
url = {https://www.rfc-editor.org/info/rfc4283},
author = {A. Patel and K. Leung and M. Khalil and H. Akhtar and K. Chowdhury},
title = {{Mobile Node Identifier Option for Mobile IPv6 (MIPv6)}},
pagetotal = 8,
year = 2005,
month = dec,
} RFC text
Contents
Network Working Group A. Patel
Request for Comments: 4283 K. Leung
Category: Standards Track Cisco Systems
M. Khalil
H. Akhtar
Nortel Networks
K. Chowdhury
Starent Networks
November 2005
Mobile Node Identifier Option for Mobile IPv6 (MIPv6)
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
Mobile IPv6 (MIPv6) defines a new Mobility header that is used by
mobile nodes, correspondent nodes, and home agents in all messaging
related to the creation and management of bindings. Mobile IPv6
nodes need the capability to identify themselves using an identity
other than the default home IP address. Some examples of identifiers
include Network Access Identifier (NAI), Fully Qualified Domain Name
(FQDN), International Mobile Station Identifier (IMSI), and Mobile
Subscriber Number (MSISDN). This document defines a new mobility
option that can be used by Mobile IPv6 entities to identify
themselves in messages containing a mobility header.
Table of Contents
1. Introduction ....................................................2
2. Terminology .....................................................3
3. Mobile Node Identifier Option ...................................3
3.1. MN-NAI Mobility Option .....................................4
3.2. Processing Considerations ..................................4
4. Security Considerations .........................................4
4.1. General Considerations .....................................4
4.2. MN-NAI Considerations ......................................4
5. IANA Considerations .............................................5
6. Acknowledgements ................................................5
7. Normative References ............................................5
8. Informative Reference ...........................................6
1. Introduction
The base specification of Mobile IPv6 [RFC3775] identifies mobility
entities using an IPv6 address. It is essential to have a mechanism
wherein mobility entities can be identified using other identifiers
(for example, a Network Access Identifier (NAI) [RFC4282],
International Mobile Station Identifier (IMSI), or an application/
deployment specific opaque identifier).
The capability to identify a mobility entity via identifiers other
than the IPv6 address can be leveraged for performing various
functions, for example,
o authentication and authorization using an existing AAA
(Authentication, Authorization, and Accounting) infrastructure or
via an HLR/AuC (Home Location Register/Authentication Center)
o dynamic allocation of a mobility anchor point
o dynamic allocation of a home address
This document defines an option with a subtype number that denotes a
specific type of identifier. One instance of subtype, the NAI, is
defined in Section 3.1. It is anticipated that other identifiers
will be defined for use in the mobility header in the future.
This option SHOULD be used when Internet Key Exchange (IKE)/IPsec is
not used for protecting binding updates or binding acknowledgements
as specified in [RFC3775]. It is typically used with the
authentication option [RFC4285]. But this option may be used
independently. For example, the identifier can provide accounting
and billing services.
2. Terminology
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Mobile Node Identifier Option
The Mobile Node Identifier option is a new optional data field that
is carried in the Mobile IPv6-defined messages that includes the
Mobility header. Various forms of identifiers can be used to
identify a Mobile Node (MN). Two examples are a Network Access
Identifier (NAI) [RFC4282] and an opaque identifier applicable to a
particular application. The Subtype field in the option defines the
specific type of identifier.
This option can be used in mobility messages containing a mobility
header. The subtype field in the option is used to interpret the
specific type of identifier.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Option Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subtype | Identifier ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option Type:
MN-ID-OPTION-TYPE has been assigned value 8 by the IANA. It is
an 8-bit identifier of the type mobility option.
Option Length:
8-bit unsigned integer, representing the length in octets of
the Subtype and Identifier fields.
Subtype:
Subtype field defines the specific type of identifier included
in the Identifier field.
Identifier:
A variable length identifier of type, as specified by the
Subtype field of this option.
This option does not have any alignment requirements.
3.1. MN-NAI Mobility Option
The MN-NAI mobility option uses the general format of the Mobile Node
Identifier option as defined in Section 3. This option uses the
subtype value of 1. The MN-NAI mobility option is used to identify
the mobile node.
The MN-NAI mobility option uses an identifier of the form user@realm
[RFC4282]. This option MUST be implemented by the entities
implementing this specification.
3.2. Processing Considerations
The location of the MN Identifier option is as follows: When present,
this option MUST appear before any authentication-related option in a
message containing a Mobility header.
4. Security Considerations
4.1. General Considerations
Mobile IPv6 already contains one mechanism for identifying mobile
nodes, the Home Address option [RFC3775]. As a result, the
vulnerabilities of the new option defined in this document are
similar to those that already exist for Mobile IPv6. In particular,
the use of a permanent, stable identifier may compromise the privacy
of the user, making it possible to track a particular device or user
as it moves through different locations.
4.2. MN-NAI Considerations
Since the Mobile Node Identifier option described in Section 3
reveals the home affiliation of a user, it may assist an attacker in
determining the identity of the user, help the attacker in targeting
specific victims, or assist in further probing of the username space.
These vulnerabilities can be addressed through various mechanisms,
such as those discussed below:
o Encrypting traffic at the link layer, such that other users on the
same link do not see the identifiers. This mechanism does not
help against attackers on the rest of the path between the mobile
node and its home agent.
o Encrypting the whole packet, such as when using IPsec to protect
the communications with the home agent [RFC3776].
o Using an authentication mechanism that enables the use of privacy
NAIs [RFC4282] or temporary, changing "pseudonyms" as identifiers.
In any case, it should be noted that as the identifier option is only
needed on the first registration at the home agent and subsequent
registrations can use the home address, the window of privacy
vulnerability in this document is reduced as compared to [RFC3775].
In addition, this document is a part of a solution to allow dynamic
home addresses to be used. This is an improvement to privacy as
well, and it affects both communications with the home agent and the
correspondent nodes, both of which have to be told the home address.
5. IANA Considerations
The values for new mobility options must be assigned from the Mobile
IPv6 [RFC3775] numbering space.
The IANA has assigned the value 8 for the MN-ID-OPTION-TYPE.
In addition, IANA has created a new namespace for the subtype field
of the Mobile Node Identifier option. The currently allocated values
are as follows:
NAI (defined in [RFC4282]).
New values for this namespace can be allocated using Standards Action
[RFC2434].
6. Acknowledgements
The authors would like to thank Basavaraj Patil for his review and
suggestions on this document. Thanks to Jari Arkko for review and
suggestions regarding security considerations and various other
aspects of the document.
7. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility
Support in IPv6", RFC 3775, June 2004.
[RFC3776] Arkko, J., Devarapalli, V., and F. Dupont, "Using IPsec
to Protect Mobile IPv6 Signaling Between Mobile Nodes
and Home Agents", RFC 3776, June 2004.
[RFC4282] Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The
Network Access Identifier", RFC 4282, November 2005.
8. Informative Reference
[RFC4285] Patel, A., Leung, K., Khalil, M., Akhtar, H., and K.
Chowdhury, "Authentication Protocol for Mobile IPv6",
RFC 4285, November 2005.
Authors' Addresses
Alpesh Patel
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
US
Phone: +1 408-853-9580
EMail: alpesh@cisco.com
Kent Leung
Cisco Systems
170 W. Tasman Drive
San Jose, CA 95134
US
Phone: +1 408-526-5030
EMail: kleung@cisco.com
Mohamed Khalil
Nortel Networks
2221 Lakeside Blvd.
Richardson, TX 75082
US
Phone: +1 972-685-0574
EMail: mkhalil@nortel.com
Haseeb Akhtar
Nortel Networks
2221 Lakeside Blvd.
Richardson, TX 75082
US
Phone: +1 972-684-4732
EMail: haseebak@nortel.com
Kuntal Chowdhury
Starent Networks
30 International Place
Tewksbury, MA 01876
US
Phone: +1 214 550 1416
EMail: kchowdhury@starentnetworks.com
Full Copyright Statement
Copyright (C) The Internet Society (2005).
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ISO Plain Language
On this page
§1Why a Node Needs Another Identifier
The base specification of Mobile IPv6 identifies mobility entities using an IPv6 address. It is essential to have a mechanism whereby mobility entities can be identified using other identifiers, for example a Network Access Identifier, an International Mobile Station Identifier, or an application or deployment specific opaque identifier.
The capability to identify a mobility entity through identifiers other than the IPv6 address can be used for several functions: authentication and authorization using an existing AAA infrastructure or via a Home Location Register and Authentication Center, dynamic allocation of a mobility anchor point, and dynamic allocation of a home address.
The document defines an option with a subtype number that denotes a specific type of identifier. One instance of the subtype, the NAI, is defined. It is anticipated that other identifiers will be defined for use in the mobility header in the future.
This option SHOULD be used when Internet Key Exchange and IPsec are not used for protecting binding updates or binding acknowledgements. It is typically used with the Mobile IPv6 authentication option, but the option may be used independently, for example to provide accounting and billing services.
An address says where a device is; a name says whose account it is. The network often needs the second one, because that is what the billing system, the subscriber database and the home address allocator all work with.
- Authentication and authorizationUse an existing AAA infrastructure, or a Home Location Register and Authentication Center.
- Choosing a mobility anchor pointAllocate the anchor point dynamically, once the node's identity is known.
- Choosing a home addressAllocate the home address dynamically rather than assigning one in advance.
- Accounting and billingThe option may be used on its own, without any authentication option.
§3The Mobile Node Identifier Option
The Mobile Node Identifier option is a new optional data field carried in the Mobile IPv6 messages that include the mobility header. Various forms of identifier can be used to identify a mobile node; two examples given are a Network Access Identifier and an opaque identifier applicable to a particular application. The Subtype field in the option defines the specific type of identifier, and it is used to interpret the identifier that follows.
The option has four fields. Option Type is MN-ID-OPTION-TYPE, assigned the value 8 by IANA, and is an 8-bit identifier of the type of mobility option. Option Length is an 8-bit unsigned integer representing the length in octets of the Subtype and Identifier fields. Subtype defines the specific type of identifier included in the Identifier field. Identifier is a variable length identifier of the type specified by the Subtype field.
The option does not have any alignment requirements.
The option is four pieces: a fixed number saying what kind of option this is, a length, a second number saying what kind of name follows, and the name itself. The name can be any length.
| Field | Name | Size | Value | Description |
|---|---|---|---|---|
OPTION-TYPE | Option Type | 1 byte | 8 | MN-ID-OPTION-TYPE, assigned the value 8 by IANA. |
OPTION-LENGTH | Option Length | 1 byte | The length in octets of the Subtype and Identifier fields. | |
SUBTYPE | Subtype | 1 byte | 1 | Defines the specific type of identifier included in the Identifier field. |
IDENTIFIER | Identifier | 1 byte | A variable length identifier of the type specified by the Subtype field. |
§3.1The NAI Subtype
The MN-NAI mobility option uses the general format of the Mobile Node Identifier option, with the subtype value of 1, and is used to identify the mobile node.
The identifier it carries has the form user@realm, as defined for the Network Access Identifier. This option MUST be implemented by the entities implementing this specification.
The one identifier defined here is the subscriber name in the form user@realm, the same shape used for roaming logins. Every implementation of this specification has to support it.
§3.2Where the Option Appears
When present, the Mobile Node Identifier option MUST appear before any authentication-related option in a message containing a mobility header.
The name goes in the message ahead of any authentication option, so that the receiving side knows who is speaking before it checks the credentials.
§4Security Considerations
Mobile IPv6 already contains one mechanism for identifying mobile nodes, the Home Address option. The vulnerabilities of the new option defined in this document are therefore similar to those that already exist for Mobile IPv6. In particular, the use of a permanent, stable identifier may compromise the privacy of the user, making it possible to track a particular device or user as it moves through different locations.
Because the Mobile Node Identifier option reveals the home affiliation of a user, it may assist an attacker in determining the identity of the user, help the attacker in targeting specific victims, or assist in further probing of the username space. These vulnerabilities can be addressed through several mechanisms. Traffic can be encrypted at the link layer, so that other users on the same link do not see the identifiers, though this does not help against attackers on the rest of the path between the mobile node and its home agent. The whole packet can be encrypted, for example when using IPsec to protect communications with the home agent. Or an authentication mechanism can be used that enables the use of privacy NAIs, that is, temporary, changing pseudonyms as identifiers.
In any case, the identifier option is only needed on the first registration at the home agent, and subsequent registrations can use the home address, so the window of privacy vulnerability is reduced compared with the base Mobile IPv6 specification. The document is also part of a solution to allow dynamic home addresses to be used, which is an improvement to privacy as well, and it affects both communications with the home agent and the correspondent nodes, both of which have to be told the home address.
A permanent identifier is trackable, so the document lists ways to limit that: encrypt the link, encrypt the whole packet, or use a name that changes. The exposure is also short, because the identifier is only needed the first time a device registers with its home agent.
- Encrypt the linkOther users on the same link do not see the identifiers, though attackers further along the path still do.
- Encrypt the whole packetFor example with IPsec protecting communications with the home agent.
- Use a changing nameAn authentication mechanism that permits privacy NAIs, that is, temporary pseudonyms.
- Use it only onceThe identifier is needed only on the first registration at the home agent; later registrations can use the home address.
§5Registry Entries
Values for new mobility options must be assigned from the Mobile IPv6 numbering space. IANA has assigned the value 8 for the MN-ID-OPTION-TYPE.
IANA has also created a new namespace for the subtype field of the Mobile Node Identifier option. The currently allocated value is the NAI, defined in RFC 4282. New values for this namespace can be allocated using Standards Action.
The option gets a number of 8, and the list of identifier kinds is a fresh registry with one entry so far, so more kinds of name can be added later.